DE102017210375A1 - Optoelectronic component with optical attenuator - Google Patents

Abstract

The invention relates to a device (10) comprising a photodetector (PD) and an electrical amplifier (TIA) connected to the photodetector (PD), the photodetector (PD) and the amplifier (TIA) being integrated in the same semiconductor substrate (11) are. According to the invention, at least one adjustable optical attenuator (30) is arranged in front of the photodetector (PD), which attenuates or at least attenuates the optical radiation reaching the photodetector (PD), an electrical output (A) of the amplifier (TIA). is directly or indirectly connected to the adjustable optical attenuator (30) and an output signal (AS) of the amplifier (TIA) or a control signal (ST) formed therewith controls the optical attenuator (30) and the photodetector (PD), the amplifier (TIA) and the attenuator (30) are integrated in the same semiconductor substrate (11).

Description

The invention relates to components with photodetector and amplifier and to methods for their operation.

From the document "A 40 Gb / s Monolithically Integrated Linear Photonic Receiver in a 0.25 μm BiCMOS SiGe: C Technology" ( Ahmed Awny, Rajasekhar Nagulapalli, Georg Winzer, Marcel Kroh, Daniel Micusik, Stefan Lischke, Dieter Knoll, Gunter Fischer, Dietmar Kissinger, Ahmet Cagri Ulusoy, Lars Zimmermann; IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, VOL. 25, NO. 7, JULY 2015 ), a device having a photodetector and an electrical amplifier connected to the photodetector is known. The photodetector and the amplifier are integrated in the same semiconductor substrate.

The invention has for its object to improve a device of the type described in terms of the quality of the electrical output signal that is output from the amplifier.

This object is achieved by a device having the features according to claim 1. Advantageous embodiments of the device according to the invention are specified in subclaims.

Thereafter, the invention provides that at least one adjustable optical attenuator is arranged in front of the photodetector, which dampens or at least attenuate reaching the photodetector optical radiation, an electrical output of the amplifier is directly or indirectly connected to the adjustable optical attenuator and an output signal the amplifier or a control signal formed therewith controls the optical attenuator and the photodetector, the amplifier and the attenuator are integrated in the same semiconductor substrate.

A significant advantage of the device according to the invention is the fact that an adjustment of the radiation power is possible by the inventively provided, adjustable optical attenuator, which falls on the photodetector. If, for example, the optical input signal at the photodetector is very large and, consequently, the electrical input signal at the input of the amplifier is very large, distortion of the electrical output signal or signals of the amplifier may occur, for example, as a result of overdriving the input stage of the amplifier. Such a signal distortion by the mentioned override can be avoided in the device according to the invention in a simple manner or at least reduced by the adjustable optical attenuator is used to limit the optical input signal of the photodetector, so the signal is already limited before the input of the photodetector and thus the Amplifier is protected.

The photodetector, the amplifier and the attenuator preferably form a closed loop.

Electrically between the electrical output of the amplifier and the optical attenuator, a control device is preferably connected, which is acted on the input side with the output signal of the amplifier output electrical output and outputs the electrical control signal for driving the optical attenuator on the output side.

The photodetector, the amplifier, the controller and the attenuator preferably form a closed loop.

The control device preferably comprises an operational amplifier.

Alternatively or additionally, it may be provided that the control device comprises a memory with a stored table, which specifies electrical control signals to be output in dependence on the output signal output by the amplifier.

The control device preferably controls the attenuator such that the average signal strength of the electrical input signal at the amplifier input of the amplifier is limited to a predetermined maximum value.

Alternatively, but also advantageously, it can be provided that the control device controls the attenuation element in such a way that the signal peaks of the electrical input signal at the amplifier input of the amplifier are limited to a predetermined maximum value.

The electrical output of the amplifier which is directly or indirectly connected to the variable optical attenuator is preferably a signal strength indicator output which outputs as the output a signal indicating the average signal strength at the amplifier input, or a signal peak detector output which outputs a signal as an output indicates the height of the signal peaks of the output signal of the amplifier.

It can also be provided that the amplifier has at least two electrical outputs namely, the output which is directly or indirectly in communication with the variable optical attenuator, and a data signal output for outputting a data signal.

With regard to the construction of the component, it is considered advantageous if a waveguide is optically coupled or connected to the photodetector and the optical attenuator acts on the waveguide. The waveguide, the photodetector and the optical attenuator are preferably integrated in the same semiconductor substrate.

It may also be advantageous if the photodetector has two or more optical inputs, to each of which a waveguide is connected.

Each of the at least two waveguides connected to the photodetector is preferably each equipped with an adjustable optical attenuator, which is indirectly or directly coupled to the or one of the outputs of the amplifier and is driven directly or indirectly by an output signal of the amplifier.

The adjustable optical attenuator may advantageously comprise a charge carrier injection device, in particular a pn or pin diode structure, or a heater, or both a charge carrier injection device and a heater.

For example, provision can be made for a charge carrier injection device and / or a heating element to be present in each of the two waveguide arms of a Mach-Zehnder structure. Such an arrangement permits operation (eg "push-pull" operation) in which either only one of the two waveguide arms with the desired sign of the change in refractive index is driven or both waveguide arms simultaneously, preferably in opposite directions or with different signs of the refractive index change.

Alternatively or additionally, it may be provided that the waveguide has an interference structure, in particular a Mach-Zehnder structure or a directional coupler structure, and / or a resonator structure, in particular a Fabry-Perot resonator structure or a ring resonator structure, and the adjustability of the attenuation of the optical attenuator based at least on a change in the refractive index in a portion of the interference structure and / or the resonator structure.

The amplifier is preferably a transimpedance amplifier, in particular one that is integrated in the same substrate as the photodetector.

Moreover, it is considered advantageous if optically a waveguide is coupled or connected to the photodetector and in and / or next to the waveguide two or more optical attenuators are arranged waveguide longitudinal direction one behind the other, each acting on the waveguide or at least can act, said each of the attenuators is in each case directly or indirectly connected to the or one of the electrical outputs of the amplifier, in particular to the same output of the amplifier, and is driven by an output signal of the amplifier, in particular the same output signal or a control signal formed therewith.

It is also advantageous if the photodiode is electrically differentially connected to the amplifier.

The invention also relates to a method of operating a device comprising a photodetector and an electrical amplifier connected to the photodetector.

With regard to such a method, the invention provides that with an output signal output at an electrical output of the amplifier or with a control signal formed therewith, an adjustable optical attenuator is activated and its attenuation is adjusted, and with the attenuator the radiation incident on the photodetector is attenuated, wherein the photodetector, the amplifier and the attenuator are integrated in the same semiconductor substrate.

With regard to the advantages of the method according to the invention, reference is made to the above statements in connection with the component according to the invention.

• 1 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, das mit einem in Lichtausbreitungsrichtung vor einem Photodetektor des Bauelements angeordneten Dämpfungsglied ausgestattet ist,
• 2 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, bei dem ein Dämpfungsglied durch eine Ladungsträgerinjektionseinrichtung gebildet ist, die eine Dämpfung optischer Strahlung durch Ladungsträgerinjektion bewirkt,
• 3 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, bei dem ein Dämpfungsglied eine Mach-Zehnder-Struktur sowie eine Ladungsträgerinjektionseinrichtung aufweist, deren injizierte Ladungsträger eine Brechzahländerung und somit eine Änderung der Interferenz am Ausgang der Mach-Zehnder-Struktur bewirken,
• 4 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, bei dem ein Dämpfungsglied einen Ringresonator sowie eine Ladungsträgerinjektionseinrichtung aufweist,
• 5 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, bei dem mehrere Dämpfungsglieder in Strahlausbreitungsrichtung vor einem Photodetektor des Bauelements angeordnet sind,
• 6 ein Ausführungsbeispiel für ein erfindungsgemäßes Bauelement, bei dem ein Photodetektor zwei Eingänge aufweist, an die jeweils ein Wellenleiter mit einem integrierten Dämpfungsglied angeschlossen ist, wobei die Dämpfungsglieder jeweils von einer individuellen Steuereinrichtung angesteuert werden,
• 7 eine Ausführungsvariante des Bauelements gemäß 6, bei dem die Dämpfungsglieder mit einer einzigen Steuereinrichtung angesteuert werden,
• 8 ein Ausführungsbeispiel für eine Steuereinrichtung, die bei den Bauelementen gemäß den 1 bis 7 eingesetzt werden kann,
• 9 ein weiteres Ausführungsbeispiel für eine Steuereinrichtung, die für den Einsatz bei den Bauelementen gemäß den 1 bis 7 geeignet ist,
• 10 eine Ausführungsvariante für ein erfindungsgemäßes Bauelement, bei dem ein Photodetektor differentiell an den Verstärker angeschlossen ist, und
• 11 eine Ausführungsvariante für ein Dämpfungsglied, bei dem zwei Wellenleiterarme einer Mach-Zehnder-Struktur, beispielsweise für einen pushpull-Betrieb, mit Brechzahländerungen mit unterschiedlichem Vorzeichen beaufschlagt werden können.

The invention will be explained in more detail with reference to embodiments; thereby show by way of example

• 1 an embodiment of a device according to the invention, which is equipped with an arranged in the light propagation direction in front of a photodetector of the device attenuator,
• 2 an embodiment of a device according to the invention, in which an attenuator is formed by a charge carrier injection device, which causes an attenuation of optical radiation by charge carrier injection,
• 3 an exemplary embodiment of a component according to the invention, in which an attenuator has a Mach-Zehnder structure and a charge carrier injection device whose injected charge carriers cause a change in refractive index and thus a change in the interference at the output of the Mach-Zehnder structure,
• 4 An exemplary embodiment of a component according to the invention, in which an attenuator has a ring resonator and a charge carrier injection device,
• 5 An embodiment of a device according to the invention, in which a plurality of attenuators are arranged in the beam propagation direction in front of a photodetector of the device,
• 6 an exemplary embodiment of a component according to the invention, in which a photodetector has two inputs, to each of which a waveguide with an integrated attenuator is connected, wherein the attenuators are each driven by an individual control device,
• 7 an embodiment of the device according to 6 in which the attenuators are driven by a single control device,
• 8th an embodiment of a control device, which in the components according to the 1 to 7 can be used
• 9 a further embodiment of a control device, which is suitable for use in the components according to the 1 to 7 suitable is,
• 10 a variant embodiment of a device according to the invention, in which a photodetector is connected differentially to the amplifier, and
• 11 a variant embodiment of an attenuator, in which two waveguide arms of a Mach-Zehnder structure, for example, for a push-pull operation, can be acted upon with refractive index changes with different signs.

For the sake of clarity, the same reference numbers are always used in the figures for identical or comparable components.

The 1 shows a component 10 that a photodetector PD and one with the photodetector PD connected electrical amplifier TIA having. At the amplifier TIA it is preferably a transimpedance amplifier.

The one with an electrical potential V acted photodetector PD upstream is an optical waveguide 20 whose in the 1 left entrance E20 for feeding optical radiation P suitable is. The optical radiation P happens the waveguide 20 in the direction of the photodetector PD , On the way to the photodetector PD the optical radiation is transmitted through a preferably into the waveguide 20 integrated or coupled to this attenuator 30 affects the optical radiation P dampens, creating a in the 1 formed with the reference numeral P 'characterized attenuated radiation.

The amplifier TIA indicates in the embodiment according to 1 a data signal output THERE on, the output side by means of optical radiation P transmitted data signal DS outputs.

The amplifier TIA also has an output A on, whose output signal AS in a control device 40 of the component 10 is fed. The control device 40 generated with the output signal AS of the amplifier TIA a control signal ST with which the attenuator 30 activated or its damping α is set.

The mentioned components of the device 10 So the waveguide 20 , the attenuator 30 , the control device 40 , the photodetector PD as well as the amplifier TIA are in the same semiconductor substrate 11 of the component 10 integrated.

By controlling the transmission change of the attenuator 30 can the light output on the photodetector PD meets, be limited. Limiting the light output can override the input stage of the amplifier TIA prevent. Overdriving the input stage with too high an input signal can cause distortion of the data signal in a disturbing way DS to lead. This distortion can be caused by too high a voltage swing, which is the input transistor of the amplifier TIA drives into saturation.

In a system with multiple parallel channels, a high signal can also cause increased crosstalk between adjacent channels. This crosstalk reduces the effective input sensitivity of the amplifier's input amplifier TIA ,

The component 10 For the reasons mentioned above, it is preferably operated in such a way that the photodetector PD , the amplifier TIA , the control device 40 and the attenuator 30 form a closed loop. Specifically, the control device 40 the activation of the attenuator 30 preferably make such that the average signal strength of the electrical input signal IT at the amplifier input Ev of the amplifier TIA is limited to a predetermined maximum value. Alternatively, the control device 40 be advantageously designed so that it operates the control loop such that the signal peaks in the electrical input signal IT at the amplifier input Ev of the amplifier TIA be limited to a predetermined maximum value.

To the described operation of the control device 40 Particularly easy to enable, it is considered advantageous when the electrical output A of the amplifier TIA to the controller 40 is connected, a signal strength indicator output is acting as the output signal AS an average signal strength at the amplifier input Ev of the amplifier TIA indicating output signal AS outputs.

Alternatively, it is considered advantageous if the electrical output A of the amplifier TIA as an output signal AS outputs a signal representing the height of the signal peaks at the amplifier input Ev of the amplifier TIA displays.

The 2 shows an embodiment of a component 10 , the construction of the component 10 according to 1 equivalent. So can be in the 2 recognize that the component 10 according to 2 a waveguide 20 , an attenuator 30 , a photodetector PD , an amplifier TIA and a control device 40 having. The attenuator 30 , the photodetector PD , the amplifier TIA and the controller 40 Form a control loop that connects to the photodetector PD falling attenuated optical power P ' adjusted to a desired level, as related to the 1 has already been explained.

In the embodiment according to 2 becomes the attenuator 30 by a charge carrier injection device 310 formed a p-doped area 311 , an n-doped area 312 and an intermediate undoped or only slightly doped middle region 313 includes, through which the waveguide 20 passed through.

To control the damping of the attenuator 30 according to 2 can the controller 40 more or less (or not at all) current in the form of the control signal ST by the charge carrier injection device 310 or whose pn or pin diode can flow; depending on the current level, the density of charge carriers within the middle area becomes 313 adjusted accordingly and thereby the attenuation of the radiation by the charge carriers in the area 313 set to the desired level. Without current, the absorption is equivalent to the absorption of the waveguide 20 itself (about 2 dB / cm) and is over typical distances of tens of microns between the attenuator 30 and the photodetector PD negligible.

For the rest, the above explanations apply in connection with 1 corresponding.

The 3 shows an embodiment of a component 10 in which an attenuator 30 through a Mach-Zehnder structure 320 is formed. The Mach Zehnder structure 320 includes two parallel waveguide arms 321 and 322 , One of the two waveguide arms, for example the lower waveguide arm 322 in 3 , is with a charge carrier injection device 310 equipped, that of the charge carrier device 310 according to 2 can correspond.

Also the charge carrier injection device 310 according to 3 indicates a p-doped region 311 and an n-doped region 312 on, which form a pn or pin diode structure, through the charge carriers in the waveguide arm 322 can be fed.

In contrast to the embodiment according to 2 in which the attenuation of the attenuator 30 is effected by the carrier attenuation of the injected charge carriers is in the embodiment according to 3 provided that of the charge carrier injection device 310 Injected carrier mainly the refractive index in the waveguide arm 322 which causes a phase shift of the optical radiation between the two waveguide arms 321 and 322 comes. Depending on the resulting phase shift at the output 323 the Mach-Zehnder structure 320 Due to the interference, there is a phase shift-dependent decoupling of the radiation and, consequently, a phase-shift-dependent amplitude of the more or less attenuated radiation P ' in the photodetector PD is irradiated.

In summary, the attenuator is based 30 So on a refractive index change by carrier injection, in contrast to the attenuator 30 according to 2 in which the attenuation is based on the attenuation by the charge carriers themselves.

In the embodiment according to 3 can the phase shift between the waveguide arms 321 and 322 alternatively or additionally by a heating element 500 be caused, which causes a change in refractive index by a change in temperature.

Incidentally, it is possible in each of the two waveguide arms 321 and 322 the Mach-Zehnder structure 320 in each case one charge carrier injection device 310 and / or a heating element 500 (eg, in the form of an electrical resistor or an electrical resistance layer) to enable, for example, operation (eg, "push-pull" operation) in which, optionally, only one of the two waveguide arms 321 and 322 is driven with the desired sign of the change in refractive index or both waveguide arms 321 and 322 simultaneously, preferably in opposite directions or with different signs of the refractive index change. Such a variant exemplifies the 11 ,

The 4 shows an embodiment of a component 10 in which an attenuator 30 a ring resonator 330 includes. The ring resonator 330 has a waveguide ring 331 and a directional coupler 332 on, the waveguide ring 331 with the waveguide 20 of the component 10 coupled.

In addition, the attenuator has 30 according to 4 a charge carrier injection device 310 on, for example, such as those associated with the 2 and 3 has already been explained above. With the charge carrier injection device 310 Charge carriers can be inserted into the waveguide ring 331 feed, whereby its effective optical length (because of the refractive index change) varies and the coupling behavior relative to the waveguide 20 is changed. The control device 40 has with the device 10 So the possibility of using the control signal ST or by means of suitable charge carrier injection into the waveguide ring 331 the coupling behavior of the ring resonator 330 relative to the waveguide 20 to influence and therefore the optical power acting on the photodetector PD meets, depending on the output signal AS at the exit A of the amplifier TIA targeted.

Regarding an optimal control of the attenuation of the attenuator 30 be to the above statements, in particular in connection with the 1 , referenced.

In the embodiment according to 4 can the phase shift in the waveguide ring 331 alternatively or additionally by a heating element 500 be caused, which causes a change in refractive index by a change in temperature.

The 5 shows an exemplary embodiment of an optical component 10 in which - in the propagation direction of the radiation P in the waveguide 20 seen - three attenuators 30 in front of a photodetector PD are arranged. The three attenuators 30 be from a controller 40 controlled, the attenuation of the attenuators 30 set such that by the three attenuators 30 , the photodetector PD , the amplifier TIA and the controller 40 formed control loop at the output A of the amplifier TIA a desired output signal AS results. Regarding the control options or with regard to the possible operation of the control device 40 be on the above statements in connection with the 1 to 4 , especially 1 , referenced.

The 6 shows an embodiment of a component 10 in which a photodetector PD two optical inputs E1 and E2 has, to each of which a waveguide is connected. The waveguides are in the 6 with the reference numerals 20 and 20 ' characterized.

Each of the two waveguides 20 and 20 ' is with an associated attenuator 30 respectively. 30 ' fitted.

One with the photodetector PD connected amplifier TIA gives at an exit A an output signal AS from two controllers 40 and 40 ' is evaluated. Each of the two control devices 40 and 40 ' controls an associated attenuator 30 and 30 ' such that the output signal AS at the exit A of the amplifier TIA has a predetermined behavior, as related to the 1 to 5 , especially 1 , has already been explained in detail above.

The 7 shows a variant of the device 10 according to 6 , In the variant according to 7 become the attenuators 30 and 30 ' from a single controller 40 driven. In addition, the above statements apply accordingly.

The 8th shows an embodiment of a control device 40 involved in the construction elements 10 according to the 1 to 7 can be used. The control device 40 according to 8th has an operational amplifier 400 as well as a resistor 410 on, which are interconnected in the manner shown. The output of the operational amplifier 400 gives the control signal ST out, that on a downstream attenuator 30 respectively. 30 ' acts as above in connection with the 1 to 7 has been explained in detail.

The 9 shows an alternative embodiment for a control device 40 involved in the construction elements 10 according to the 1 to 7 can be used. The control device 40 according to 9 has a computing device 450 as well as a memory 460 on. In the store 460 is a table TA stored, the electrical output control signals ST depending on one of an upstream amplifier TIA output signal output AS pretends. Depending on the output signal AS becomes the computing device 450 using the memory 460 or the table TA stored therein a suitable control signal ST generate and output side output for driving a downstream attenuator.

The 10 shows an alternative embodiment of a device according to the invention 10 in which a photodetector PD differentially to the amplifier TIA connected. For this purpose, the amplifier points TIA two amplifier inputs Ev and Ev ' on, in each case an input signal IT respectively. IT' of the photodetector PD is fed. Incidentally, the above statements apply in connection with the 1 to 9 corresponding.

Summarized above in connection with the embodiments according to the 1 to 11 Devices and methods described in which the optical signal can be attenuated before the photodetector. The amplifier can thus be optimized for maximum sensitivity without the risk of overloading.

The integration of electronic and photonic elements in one and the same semiconductor substrate 11 (preferably silicon substrate) or on an integrated circuit (E-PIC) offers the possibility of the input signal IT optically limit and thus to optimize the sensitivity of the input stage. The realization is unique in its compactness, cost-effectiveness and avoids a compromise in the sensitivity of the receiver.

The amplifier TIA preferably has a data signal output THERE for the data signal DS at a data rate of, for example, 25 Gbit / s and an additional output for the output signal AS , The output signal AS For example, the signal strength (received signal strength indicator, RSSI) or the peak amplitude at the amplifier input Ev represent (peak detector).

Possible applications include optical data transmission in and between data centers ("intra DC" and "inter DC"), optical data transmission in the metro network and to the end user ("Fiber to the home, FTTH").

The device according to the in the 1 to 11 The exemplary embodiments shown are suitable for optical data transmission at 100 Gbit / s, as regulated by the CWDM4-MSA and by the IEEE Standard 100GBase-LR4, for example. In both cases, a large dynamic range is required for the received optical power, from a minimum average power of -11.5dBm (CWDM4) and -10dBm (LR4) to a maximum of 2.5dBm (CWDM4 and LR4).

• - Die Begrenzung des optischen Eingangssignals ES auf dem Photodetektor PD kann eine Verzerrung der elektrischen Signale an dem Datensignalausgang DA und dem Ausgang A des Verstärkers verhindern.
• - Die Regelung der Ausgangsamplitude ist ohne Änderung der Verstärkungsparameter des Verstärkers und somit ohne eine Reduktion der Empfängerempfindlichkeit möglich.
• - Durch eine kurze elektrische Verbindung zwischen Photodiode und Verstärker wird die Empfindlichkeit der Verstärkereingangsstufe erhöht.
• - Keine zusätzlichen optischen Einfügeverluste durch den Abschwächer 30 (bzw. vernachlässigbar bei Verwendung einer p-i-n Diode)
• - Keine Überspannungen bei hohen optischen Eingangsleistungen
• - Der optische Abschwächer kann bei hohen Signalwerten eingesetzt werden, um einen Einfluss auf die Empfindlichkeit zu vermeiden. Ohne optischen Abschwächer müsste sonst die Empfindlichkeit des Verstärkers durch eine Änderung der Transimpedanz mittels eines Varistors angepasst werden, auf Kosten der Empfindlichkeit.
• - Das gesamte beschriebene Empfängersystem kann sehr kompakt realisiert werden.
• - Kurze Signallaufzeiten und eine vereinfachte Herstellung mit wenig Komponenten
• - Es müssen keine externen optischen oder elektronischen Komponenten zum Einsatz kommen, so dass keine durch solche Komponenten unvermeidbaren zusätzlichen Signalverluste auftreten.
• - Der optische Abschwächer kann eine typische maximale Signalunterdrückung von mindestens 5 dB erzeugen.
• - Das Substratmaterial des Bauelements (bzw. integrierten EPIC Chips) kann Silizium sein.
• - Die Photodiode kann zwei oder mehr optische Eingänge aufweisen, an die jeweils ein Wellenleiter angeschlossen ist. Das Summensignal aller Eingänge bestimmt dann die Verstärkungskontrolle. Dabei kann sowohl ein optischer Abschwächer die Transmission beider Wellenleiter regeln, wenn diese sich aus einem Wellenleiter aufgeteilt haben, als auch jeder Wellenleiter einen eigenen optischen Abschwächer besitzen, wodurch eine unabhängige Regelung ermöglicht wird.
• - Die Photodiode kann eine Ge-PD sein.
• - Die Photodiode kann elektrisch differentiell an den Verstärker (TIA) angeschlossen sein.
• - Über die Änderung allein der Brechzahl kann eine Änderung der Phase des empfangenen Signals durchgeführt werden. In Kombination mit einem lokalen Oszillator als Teil eines kohärenten Empfängers mit einer balanced Photodiode kann damit der Arbeitspunkt stabilisiert werden.
• - Einkopplung des optischen Signals in den Wellenleiter kann über einen Gitterkoppler geschehen.

The above related to the 1 to 11 described embodiments, the cointegration of waveguides 20 , optical attenuator (attenuator) 30 , Photodetector PD , Amplifier TIA and control circuit on an EPIC may have individual, several or all of the following characteristics and / or advantages:

• - The limitation of the optical input signal IT on the photodetector PD may be a distortion of the electrical signals at the data signal output THERE and the exit A prevent the amplifier.
• - The regulation of the output amplitude is possible without changing the gain parameters of the amplifier and thus without a reduction of the receiver sensitivity.
• - A short electrical connection between photodiode and amplifier increases the sensitivity of the amplifier input stage.
• - No additional optical insertion losses through the attenuator 30 (or negligible when using a pin diode)
• - No overvoltages at high optical input powers
• - The optical attenuator can be used at high signal levels to avoid any influence on the sensitivity. Without an optical attenuator, the sensitivity of the amplifier would have to be adjusted by changing the transimpedance by means of a varistor at the expense of sensitivity.
• - The entire described receiver system can be realized very compact.
• - Short signal transit times and simplified production with few components
• - There are no external optical or electronic components are used, so that no unavoidable by such components additional signal losses occur.
• - The optical attenuator can produce a typical maximum signal suppression of at least 5 dB.
• The substrate material of the component (or integrated EPIC chip) may be silicon.
• - The photodiode may have two or more optical inputs, to each of which a waveguide is connected. The sum signal all inputs then determines the gain control. In this case, both an optical attenuator regulate the transmission of both waveguides, if they have divided from a waveguide, as well as each waveguide own optical attenuator, whereby an independent control is possible.
• - The photodiode can be a PD be.
• - The photodiode can be electrically differentially connected to the amplifier ( TIA ).
• - By changing only the refractive index, a change in the phase of the received signal can be performed. In combination with a local oscillator as part of a coherent receiver with a balanced photodiode, the operating point can thus be stabilized.
• - Coupling of the optical signal in the waveguide can be done via a grating coupler.

While the invention has been further illustrated and described in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

10

module

11

Semiconductor substrate

20

waveguides

20 '

waveguides

30

attenuator

30 '

attenuator

40

control device

40 '

control device

310

Charge carrier injection device

311

p-doped area

312

n-doped area

313

middle area

320

Mach-Zehnder structure

321

waveguide arm

322

waveguide arm

323

output

330

ring resonator

331

Optic ring

332

directional coupler

400

operational amplifiers

410

resistance

450

computing device

460

Storage

500

heating element

A

output

AS

output

THERE

Data signal output

DS

data signal

E1

entrance

E2

entrance

E20

entrance

IT

input

IT'

input

Ev

amplifier input

Ev '

amplifier input

P

Radiation / optical power

P '

damped radiation

PD

photodetector

ST

control signal

TA

table

TIA

amplifier

V

potential

α

damping

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Ahmed Awny, Rajasekhar Nagulapalli, Georg Winzer, Marcel Kroh, Daniel Micusik, Stefan Lischke, Dieter Knoll, Gunter Fischer, Dietmar Kissinger, Ahmet Cagri Ulusoy, Lars Zimmermann; IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, VOL. 25, NO. 7, JULY 2015 [0002]

Claims (21)

A device (10) comprising a photodetector (PD) and an electrical amplifier (TIA) connected to the photodetector (PD), the photodetector (PD) and the amplifier (TIA) being integrated in the same semiconductor substrate (11), characterized in that - in front of the photodetector (PD) at least one adjustable optical attenuator (30) is arranged, which attenuates the optical radiation reaching the photodetector (PD) or at least attenuate, - an electrical output (A) of the amplifier (TIA) directly or indirectly is in communication with the variable optical attenuator (30) and an output signal (AS) of the amplifier (TIA) or a control signal (ST) formed therewith drives the optical attenuator (30); and - the photodetector (PD), the amplifier (TIA ) and the attenuator (30) are integrated in the same semiconductor substrate (11). Component (10) according to Claim 1 , characterized in that the photodetector (PD), the amplifier (TIA) and the attenuator (30) form a closed loop. Device (10) according to one of the preceding claims, characterized in that electrically connected between the electrical output (A) of the amplifier (TIA) and the optical attenuator (30) is a control device (40) whose input side with that at the output ( A) of the amplifier (TIA) output electrical output signal (AS) is applied and output side, the electrical control signal (ST) for driving the optical attenuator (30) outputs. Component (10) according to Claim 3 , characterized in that the photodetector (PD), the amplifier (TIA), the control device (40) and the attenuator (30) form a closed control loop. Component (10) according to one of the preceding claims, characterized in that the control device (40) comprises an operational amplifier (400). Component (10) according to one of the preceding claims, characterized in that the control device (40) comprises a memory (460) with a stored table (TA), the output electrical control signals in response to the output from the amplifier (TIA) output signal (AS ) pretends. Component (10) according to one of the preceding claims, characterized in that the control device (40) controls the attenuator (30) such that the average signal strength of the electrical input signal (ES) at the amplifier input (Ev) of the amplifier (TIA) to a predetermined Maximum value is limited. Component (10) according to one of the preceding claims, characterized in that the control device (40) controls the attenuator (30) such that the signal peaks of the electrical input signal (ES) at the amplifier input (Ev) of the amplifier (TIA) to a predetermined maximum value be limited. Component (10) according to any one of the preceding claims, characterized in that the electrical output (A) of the amplifier (TIA) which is directly or indirectly connected to the adjustable optical attenuator (30) is a signal strength indicator output called the output signal (AS) outputs a signal indicating the average signal strength at the amplifier input (Ev) of the amplifier (TIA). Component (10) according to one of the preceding Claims 1 to 8th characterized in that the electrical output (A) of the amplifier (TIA) directly or indirectly connected to the variable optical attenuator (30) is a signal peak detector output which outputs as output (AS) a signal representing the magnitude the signal peaks at the amplifier input (Ev) of the amplifier (TIA). Component (10) according to one of the preceding claims, characterized in that the amplifier (TIA) has at least two electrical outputs, namely the output (A) which is directly or indirectly in communication with the adjustable optical attenuator (30), and a Data signal output (DA) for outputting a data signal (DS). Component (10) according to one of the preceding claims, characterized in that - a waveguide (20) is optically coupled or connected to the photodetector (PD) and the optical attenuator (30) acts on the waveguide (20) and - the waveguide ( 20), the photodetector (PD) and the optical attenuator (30) are integrated in the same semiconductor substrate (11). Component (10) according to one of the preceding claims, characterized in that the photodetector (PD) has two or more optical inputs (E1, E2), to each of which a waveguide (20, 20 ') is connected. Component (10) according to Claim 13 characterized in that each of the at least two waveguides (20, 20 ') connected to the photodetector (PD) is each provided with an adjustable optical attenuator (30, 30') which is directly or indirectly connected to the or one of the outputs of the amplifier (TIA) is coupled and indirectly or directly controlled by an output signal (AS) of the amplifier (TIA). Component (10) according to one of the preceding claims, characterized in that the adjustable optical attenuator (30) comprises a charge carrier injection device (310), in particular a pn or pin diode structure, and / or a heating device. Component (10) according to one of the preceding claims, characterized in that - the waveguide (20) has an interference structure, in particular a Mach-Zehnder structure (320) or a directional coupler structure (332), and / or a resonator structure, in particular a Fabry Perot resonator structure or a ring resonator structure (330), and - the adjustability of the attenuation of the optical attenuator (30) based at least on a change in the refractive index in a portion of the interference structure and / or the resonator structure. Component (10) according to one of the preceding claims, characterized in that the amplifier (TIA) is a transimpedance amplifier, in particular one which is integrated in the same substrate (11) as the photodetector (PD). Component (10) according to one of the preceding claims, characterized in that - a waveguide (20) is optically coupled or connected to the photodetector (PD) and - two or more optical attenuators (30) are provided in and / or next to the waveguide (20) ) are arranged in waveguide longitudinal direction one behind the other, each acting on the waveguide (20) or at least can act, - each of the attenuators (30) each directly or indirectly with the or one of the electrical outputs of the amplifier (TIA), in particular with the same output (A) of the amplifier (TIA), is in communication and with an output signal (AS) of the amplifier (TIA), in particular the same output signal (AS), or a control signal (ST) formed therewith is driven. Component (10) according to one of the preceding claims, characterized in that the photodiode (PD) is electrically differentially connected to the amplifier (TIA). Method for operating a component (10) comprising a photodetector (PD) and an electrical amplifier (TIA) connected to the photodetector (PD), characterized in that - one connected to an electrical output (A) of the amplifier (TIA) output signal (AS) or with a control signal (ST) formed therewith, an adjustable optical attenuator (30) is driven and its attenuation is adjusted, and - with the attenuator (30) the radiation falling on the photodetector (PD) is attenuated, wherein the photodetector (PD), the amplifier (TIA) and the attenuator (30) are integrated in the same semiconductor substrate (11). Method according to Claim 20 , characterized in that the attenuation is adjusted such that the output signal (AS) at the output (A) of the amplifier (TIA) does not exceed a predetermined threshold.

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